1/(1+e^x)dx
I saw this problem on baidu
http://post.baidu.com/f?kz=236753020 is the url
I first tried by parts, you let u to be 1/(1+e^x) and v\' to be dx, but it didn\'t work so well. Then i was trying to play w/ the fraction, like multiply both sides by (1-e^x)/(1-e^x), and it didn\'t work out either.
I used to so good at this kind of problems back in the old days, but b/c i haven\'t practiced for so long, my calculus skill deterioated gradually. Anyway, any smarties know how to solve this problem?
